Acclimation of the Hapalosiphon sp. (Cyanoprokaryota) to combination effects of dissolved inorganic carbon and pH at extremely limited irradiance.

摘要

Acclimation studies on algal flora of rice fields are less attended. In this paper, some physiological properties of ecophysiologically unexplored species Hapalosiphon sp. was evaluated in combination of limited irradiance, different pHs and different inorganic carbon availability. Ammonium excretion increased at pH 9 when carbon dioxide content tended to limited or extremely limited but differences were not significant. Chlorophyll content at pH 9 was higher regardless of DIC conditions. Adaptation to pH 9 gave rise to a increasing of PBP contents, phycobilisome numbers and PSII/PSI ratio. The maximum nitrogenase activity was seen in cells grown at pH 9 and DIC availability. Dimensions of heterocysts in the day 4 after inoculation corresponded with the maximum nitrogenase activity. The amount of total carbohydrate and protein were significant between pH 7 and pH 9 especially at higher DIC content. Carotenoids were not affected by pH and DIC availability at such a limited irradiance. Collectively results indicated that Hapalosiphon sp. is an alkalopilic cyanobacterium and adapts to combined variation of pH and carbon dioxide at extremely limited irradiance in the range usually found in rice fields.